When you remove the volume of the lung from the equation however (which is what happens when you divide DLCO by VA), all you can measure is how quickly carbon monoxide decreases during breath-holding (KCO). DLCO however, is highest at TLC and lowest at FRC and this is because it is primarily a measurement of functional gas exchange surface area (and not the rate at which CO disappears). At the time the article was last revised Patrick J Rock had no recorded disclosures. Standardized single breath normal values for carbon monoxide diffusing capacity. There is no particular consensus about what constitutes an elevated KCO however, and although the amount of increase is somewhat dependent on the decrease in TLC, it is not predictable on an individual basis. Johnson DC. The diagnostic value of KCO is pretty much limited to restrictive lung defects and can only be used to differentiate between intrinsic and extrinsic causes for a reduced DLCO. Scarring and a loss of elasticity causes the lung to become stiffer and harder to expand which decreases TLC. In restrictive lung diseases and disorders. <>/ProcSet[/PDF/Text/ImageB]/XObject<>>>/Type/Page>> Could that be related to reduced lung function? DLCO studies should go beyond reporting measured, 29 0 obj Do you find that outpatient rehabilitation is effective for your patients with multiple sclerosis? xb```c`` b`e` @16Y1 vLE=>wPTPt ivf@Z5" X, Most people have a diagnosis such as copd so hopefully you will get yours soon. 2011, Jaypee Brothers Medical Publishers, Ltd. Horstman MJM, Health B, Mertens FW, Schotborg D, Hoogsteden HC, Stam H. Comparison of total-breath and single-breath diffusing capacity if health volunteers and COPD patients. As stone says the figures relate to the gas exchanging capacities of your lungs,the ct scan once interpreted by a radiological consultant will give all the info your consultant needs to give you an accurate diagnosis of your condition and hopefully the best treatment plan for the future. The diagnosis often is made after an unexpectedly reduced Dlco prompts a search for the reasons. A test of the diffusing capacity of the lungs for carbon monoxide (DLCO, also known as transfer factor for carbon monoxide or TLCO), is one of the most clinically valuable tests of lung function. The technique was first described 100 years ago [ 1-3] and J.M.B. Two, this would also lead to an increase in the velocity of blood flow and oxygen may not have sufficient time to diffuse completely because of the decrease in pulmonary capillary residence time. Why do we have to keep on ,time and time again asking some professionals about our own test results . Single breath methods are used to determine the rate constant of the alveolar uptake of carbon monoxide (CO) for 10 s at barometric pressure, that is, transfer coefficient of the lung for CO (Kco) and alveolar volume (V A) (Krogh, 1915; Hughes and Pride, 2012).Kco more sensitively reflects the uptake efficiency of alveolar-capillary DLCO is best thought of as a measurement of the functional gas exchange surface area of the lung. Carbon monoxide transfer coefficient (transfer factor/alveolar volume) in females versus males. <> 105 (8): 1248-56. The results will depend on your age, height, sex and ethnicity as well as the level of haemoglobin in your blood. [Note: looking at the DLCO and TLC reference equations I have on hand, for a 50 y/0 175 cm male predicted TLC ranges 5.20 to 7.46 and predicted DLCO ranges from 24.5 to 37.1. Kaminsky DA, Whitman T, Callas PW. It is very frustrating not to get the results for so long. Ejection fraction is a measurement of the percentage of blood leaving the heart each time it squeezes. For example, if the patient has a disease that causes a decrease in lung surface area, or has had a lung removed, then there is a decrease in transfer factor but there is a normal KCO. You breathe in air containing tiny amounts of helium and carbon monoxide (CO) gases. endobj How about phoning your consultants secretary in about ten days time? the rate at which the concentration of CO disappears increases) the DLCO (the actual volume of CO absorbed) decreases. 31 0 obj <> endobj 0000008215 00000 n endobj Finally I always try to explain to the trainee physicians that VA is simply the volume of lung that that has been exposed to the test gas and may not reflect the true alveolar volume. This site uses Akismet to reduce spam. It is important to remember that the VA is measured from an expiratory sample that is optimized for measuring DLCO, not VA. 0000003645 00000 n If, on the other hand, the patient performs a Muller maneuver (attempts to inhale forcefully against the closed mouthpiece) this will cause negative pressure inside the lung and will increase the capillary blood volume. The reason Kco increases with lower lung volumes in certain situations can best be understood by the diffusion law for gases. Spirometry is performed simultaneously with measurement of test gas concentrations in order to calculate Va and Kco to derive Dlco, which then is adjusted for hemoglobin concentration. And probably most commonly there is destruction of the alveolar-capillary bed which decreases the pulmonary capillary blood volume and the functional alveolar-capillary surface area. We're currently reviewing this information. Would be great to hear your thoughts on this! xref 1. Thank u. I have felt unwell for about 4 months and am wondering if it could be the reduced lung function causing it as I initially thought it was a heart issue. Although it is nonspecific, a reduced Dlco requires an adequate explanation in every case. This means that when TLC is reduced but the lung tissue is normal, which would be the case with neuromuscular diseases or chest wall diseases, then KCO should be increased. Whenever Dlco is reduced, the predominant reason for this reduction (eg, whether it is predominantly a reduced Va, or reduced Kco, or both) has critical diagnostic and pathophysiologic implications. But the fact is that for regular DLCO testing any missing fraction isnt measured so it really isnt possible to say what contribution it would have made to the overall DLCO. Asthma and Lung UK is a company limited by guarantee 01863614 (England and Wales). For example, group 1 PAH, early pulmonary vasculitis, and pulmonary arteriovenous malformations may produce a lower than predicted Dlco primarily due to a reduction in Kco or due to reduced Vc, while Va remains relatively preserved (see equation 6). The ratio of these two values is expressed as a percentage. Diaz PT, King MA, Pacht, ER et al. To one degree or another a reduced VA/TLC ratio is an artifact of the DLCO measurement requirements. a change in concentration between inhaled and exhaled CO). If KCO is low with a low VA, then we also have to consider the possibility of reduction in alveolar volume (for whatever reason) in conjunction with parenchymal changes. Because, in both disease entities, pulmonary congestion is present and then DLCO and KCO should be increased. Therefore, Dlco is defined as follows: Pb is atmospheric pressurewater vapor pressure at 37C, and Kco is kco/Pb. 0000126565 00000 n Webdicted normal values, that is, those recommended by Cotes (1975). KCO is only a measurement of the rate at which CO disappears during breath-holding (i.e. practitioner should be consulted for diagnosis and treatment of any and all medical conditions. For a given gas, the rate of diffusion for this gas, Dl, is dependent upon the thickness of the diffusing membrane (DM, the alveolar-capillary membrane), the rate of uptake of a gas by red blood cells, , and the pulmonary capillary blood volume, Vc. 0000002265 00000 n Become a Gold Supporter and see no third-party ads. Samuel Louie, MD, is a professor of medicine in the Division of Pulmonary, Critical Care, and Sleep Medicine at UC Davis Medical Center. 0000002468 00000 n KCO has a more limited value when assessing reduced DLCO results for obstructive lung disease. This rate, kco, which has units of seconds-1, is calculated as follows: COo is the initial alveolar concentration, COe is the alveolar concentration at the end of the breath hold, and t is the breath-hold time in seconds. If youd like to see our references get in touch. You also state that at FRC (during expiration) ..an increase in pulmonary capillary blood volume.. Im getting a little confused. Pulmonary function testing and interpretation. I dont know if this is the case for pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis since they are both rare and under-diagnosed. Carbon monoxide transfer coefficient (often abbreviated as KCO) is a parameter often performed as part of pulmonary function tests. This value is an expression of the gas transfer ability per unit volume of lung. The patient breathes through a mouthpiece with nose clips in place to acclimate to the equipment, followed by unforced exhalation to residual volume (RV). Finally DLCO tests have to meet the ATS/ERS quality standards for the KCO to be of any use and what we consider to be normal or abnormal about DLCO, VA and KCO depends a lot on the reference equations we select. Neder JA, Marillier M, Bernard AC, O'Donnell DE. A gas transfer test is used to help diagnose and monitor lung conditions including COPD and pulmonary fibrosis. Expressed as a percentage of the value at predicted TLC (zV These individuals have an elevated KCO to begin with and this may skew any changes that occur due to the progression of restrictive or obstructive lung disease. 20 0 obj Making me feel abit breathless at times but I'm guess it's because less oxygen than normal is circulating in my blood. This doesnt mean that KCO cannot be used to interpret DLCO results, but its limitations need to recognized and the first of these is that the rules for using it are somewhat different for restrictive and obstructive lung diseases. This is not necessarily true and as an example DLCO is often elevated in obesity and asthma for reasons that are unclear but may include better perfusion of the lung apices and increased perfusion of the airways. This measures how well the airways are performing. Respir Med 2000; 94:28. Lower than normal hemoglobin levels indicate anemia. Haemoglobin is the protein in red blood cells that carries oxygen. Predicted KCO derived from these values would range from 3.28 to 7.13!] She wont give you the results but she will tell the consultant of your concerns. endobj Despite this, Va typically approximates TLC within a few percentage points (Va/TLC>95%) in the normal lung. strictly prohibited. 0000017721 00000 n 2023 Realistically, the diagnosis of a reduced DLCO cannot proceed in isolation and a complete assessment requires spirometry and lung volume measurements as well. endobj You will be asked to take in a big breath through a mouthpiece while wearing a nose clip. 5. Hughes JMB, Pride NB. Examination of the carbon monoxide diffusing capacity (DLCO) in relation to its KCO and VA components. 3. This information uses the best available medical evidence and was produced with the support of people living with lung conditions. I have no idea what any of the above percentages mean or 'parenchymal' means. btw the figures don't look dramatically bad but then again i am only a retired old git with a bit of google related knowledge and a DLCO figure that would scare the pants of you lol . Interpretation of KCO depends on other parameters such as. It also indicates that 79% to 60% of predicted is a mild reduction, 59% to 40% is a moderate reduction, and that Dlco values less than 40% of predicted are severely reduced. The exhaled breath from alveolar lung volume is collected after the washout volume (representing anatomic dead space) and is discarded as described in the Figure. After elimination of estimated dead-space exhaled breath, a volume of exhaled breath is sampled to measure test gas concentrations (, Va is calculated by a change in the concentration of an inhaled inert gas (such as helium or methane) after that gas has had an opportunity to mix throughout the lungs. Decreased volume of pulmonary capillary blood or hemoglobin volume, Decreased surface area integrated between capillaries and alveoli, Ventilation/perfusion mismatching or intrapulmonary shunting from atelectasis, The patient needs to hold his or her breath for 10 seconds, then exhale quickly and completely back to RV. weakness) then the TLCO is low but the KCO is normal or increased. 0000002029 00000 n This is where I get to say Im a technologist not a diagnostician but I do think about issues like this fairly often so this is my take on these disorders: Pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis are both forms of pulmonary hypertension with a progressive occlusion of the pulmonary circulation. Because an inert gas is used, it is reasonably assumed that a change in exhaled concentration from the inhaled concentration is purely due to redistribution (dilution) of the gas into a larger volume. 0000022334 00000 n The presence of the following suggests the diagnosis of amiodarone-induced lung disease: new or worsening symptoms or signs; new abnormalities on chest radiographs; and a decline in TLC of 15% or more, or a decline in Dlco of more than 20%. A high KCO can be due to increased perfusion, a thinner alveolar-capillary membrane or by a decreased volume relative to the surface area. Neutrophils are the most plentiful type, making up 55 to 70 percent of your white blood cells. endobj Authors: In the setting of a normal chest radiograph, early ILD or pulmonary vascular disease or both can be present. A fit young adult may have a KCO of approximately 1.75 mmol/min/kPa/litre, an elderly adult may be about 1.25. 0000046665 00000 n I may be missing something but Im not quite sure what you expect KCO to be. xokOpcHL# Ja3E'}F>vVXq\qbR@r[DUL#!1>K!-^L(_qG@'t^WDb&R!4Ka7|EtpfUP3rDKN"D]vBYG2dQ@@xVk*T=3%P0oml J l, Dlco correction by Va cannot reliably rule out the presence of underlying emphysema or parenchymal lung disease.4, Dlco usually is decreased in COPD when emphysema is present; it typically is normal in chronic bronchitis alone or in asthma, where it even could be increased during acute attacks.5. Transfer coefficient of the lung for carbon monoxide and the accessible alveolar volume: clinically useful if used wisely. For this reason, in my lab a KCO has to be at least 120 percent of predicted to be considered elevated (and I usually like it to be above 130% to be sufficiently confident). application/pdf 94 (1): 28-37. to assess PFT results. Hemangiomatosis is accompanied with a proliferation of pulmonary capillaries and fibrosis while veno-occlusive disease isnt. (2011) Respiratory medicine. D:20044910114917 These are completely harmless at the very low levels used. At the time the article was created Yuranga Weerakkody had no recorded disclosures. <]>> Low Dlco less than or equal to 50% predicted can predict hypoxemia with exercise. Chest wall disease, such as morbid obesity, pleural effusions, and kyphoscoliosis, can display a normal Dlco or a slightly decreased Dlco, but the Dlco/Va remains normal. useGPnotebook. left-to-right shunt and asthma), extra-vascular hemoglobin (e.g. Hi Richard I have been ejoying your posts for a while now and have forwarded on the link to my colleagues here at Monash. 0000001782 00000 n Chest area is tender. Immune, Lipid Biomarkers May Predict Onset of Atopic Dermatitis in Infants, Treatment for Type 2 Diabetes Reduces Major CV Events in Men, Inflammation Reduction Medications May Lower Dementia Risk in Patients With Rheumatoid Arthritis, Sepsis Increases Risk of Post-Discharge Cardiovascular Events, Death, AHA Releases Statement on Hypertension Induced by Anticancer Therapy, Consultant360's Practical Updates in Primary Care. inhalation to a lung volume below TLC), then DLCO may be underestimated. To see content specific to your location, When the heart squeezes, it's called a contraction. you and provide you with the best service. For the COPD patients at least part of the improvement was due to an increase in the measured VA. Conditions associated with severe carbon monoxide diffusion coefficient reduction. KCO is probably most useful for assessing restrictive lung diseases and much that has been written about KCO is in reference to them. Spirometer parameters were normal. The Fick law of diffusion can explain factors that influence the diffusion of gas across the alveolar-capillary barrier: V is volume of gas diffusing, A is surface area, D is the diffusion coefficient of gas, T is the thickness of the barrier, and P1P2 is the partial pressure difference of gas across the alveolar-capillary barrier. It may also be used to assess your lungs before surgery, or to see how a persons lungs react when having chemotherapy. Dlco is the product of Va and Kco, the rate of diffusion across a membrane that is dependent upon the partial pressure of the gas on each side of the alveolar membrane. Due for review: January 2023. The patient needs to hold his or her breath for 10 seconds, then exhale quickly and completely back to RV. By itself KCO is nothing more the rate at which CO disappears during breath-holding and the reduced DLCO already says theres a diffusion defect. This means that when TLC is reduced and there is interstitial involvement, a normal KCO (in terms of percent predicted) is actually abnormal. To see Percent Prediced, you must enter observed FVC, FEV1, and FEF25-75% values in the appropriate boxes. Ruth. Saydain G, Beck KC, Decker PA, Cowl CT, Scanlon PD. I also have some tachycardia on exertion, for which I am on Bisoprolol 1.25 mg beta blocker. But a cornucopia of lung disorders that disturb oxygen uptake by hemoglobin in the lungs (and increase the work of breathing, perceived as dyspnea) can be detected by a reduction in Dlco. Respiratory tract symptoms and abnormalities on chest radiographs and/or chest computed tomography (CT) scans are essential to properly interpret any PFT, including Dlco. As is made obvious in equation 5, reductions in either Va or Kco (aka, Dlco/Va) will result in a reduction in Dlco. The pathophysiology of pulmonary diffusion impairment in human immunodeficiency virus infection. VA is a critical part of the DLCO equation however, so if VA is reduced because of a suboptimal inspired volume (i.e. Johnson DC. UB0=('J5">j7K\]}R+7M~Z,/03`}tm] upgrade your browser. Hughes, N.B. alveolar hemorrhage), a low KCO: could suggest intra-parenchymal restriction with impaired gas exchange efficiency as in some interstitial lung diseases (ILD), a normal KCO: could suggest intra-parenchymal restriction with preserved KCO (can be a common finding in patients with HRCT abnormalities showing a pattern consistent with idiopathic interstitial pneumonia);normal KCO, therefore, should not be misinterpreted as no ILD, ADVERTISEMENT: Supporters see fewer/no ads, Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. 0000009603 00000 n The corrected value is referred to as the DLCO/VA and a normal value is considered to be 80% or more of the predicted value. Patients with emphysema have low DLCO, Kco, DACO,and KAco. I agree with you that a supranormal KCO (120%) is highly suggestive of a true volume effect. After elimination of estimated dead-space exhaled breath, a volume of exhaled breath is sampled to measure test gas concentrations (Figure). <>/ProcSet[/PDF/Text/ImageB]/XObject<>>>/Type/Page>> The term DL/VA is misleading since the presence of VA implies that DL/VA is related to a lung volume when in fact there is no volume involved. They are often excellent and sympathetic. The result of the test is called the transfer factor, or sometimes the diffusing capacity. These findings are welcome as they provide significant insight into the long-term lung function impairment associated with COVID-19. The answer is maybe, but probably not by much. Importance of adjusting carbon monoxide diffusing capacity (DLCO) and carbon monoxide transfer coefficient (KCO) for alveolar volume. Therefore, the rate of CO uptake is calculated from the difference between the initial and final alveolar CO concentrations over the period of a single breath-hold (10 seconds). kco normal range in percentage. A checklist can be helpful in establishing a regular routine for interpreting Dlco, Va and Kco (Tables 2 and3). Any knowledge gratefully received. It is a common pitfall to correct Dlco for Va and thus misinterpret Dlco/Va that appears in the normal range in patients with obstructive lung diseases such as COPD and asthma-COPD overlap syndrome (ACOS), which can produce spuriously normal results, leading to errors in interpretation and decision-making. A reduction in Va will reduce Dlco unless the rate of CO uptake or Kco increases. This could lead to a couple additional issues; one, that the depth of the pulmonary capillary around ventilated alveoli is increased and this may prevent the diffusion of oxygen to the blood furthest away from the alveolar membrane. Oxbridge Solutions Ltd. The cause of the diffusion defect is a large scale V-Q mismatch but that doesnt look any different from somebody with PVOD/PCH with a DLCO and KCO that were 50% of predicted and where the V-Q mismatch is occurring on a much smaller scale. 4 0 obj PAH can cause lung restriction but from what I know the effect is fairly homogeneous. Not really, but it brings up an interesting point and that is that the VA/TLC ratio indicates how much of the lung actually received the DLCO test gas mixture (at least for the purposes of the DLCO calculation). Learn how your comment data is processed. The American Thoracic Society/European Respiratory Society statement on PFT interpretation advocates the use of a Dlco percent predicted of 80% as the normal cutoff. The specificity and sensitivity of Dlco for specific lung diseases has not been studied extensively until recently, particularly for pulmonary arterial hypertension (PAH) and systemic sclerosis with or without interstitial lung disease (ILD). As an example, if a patient had a pulmonary emboli that blocked blood flow to one lung then DLCO would be about 50% of predicted, but in these circumstances KCO would also be 50% of predicted. Similarly, it is important to recognize the conditions that most frequently are associated with an elevated or high Dlco (ie, greater than 140% predicted)namely asthma, obesity, or both and, uncommonly, polycythemia and left-to-right shunts.6 Any condition that typically reduces Dlco, such as emphysema, pulmonary vascular disease, or cancer, can deceptively bring supranormal Dlco into the normal range. Top tips for organising a brilliant charity quiz, Incredible support from trusts and foundations, Gwybodaeth yng Nghymraeg / Welsh language health information, The Asthma UK and British Lung Foundation Partnership, Why you'll love working with the British Lung Foundation, Thank you for supporting the British Lung Foundation helpline. VAT number 648 8121 18. We are busy looking for a solution. Lung Function. It would actually be more complicated because of the if-thens and except-whens. Notify me of follow-up comments by email. [Note: The value calculated from DLCO/VA is related to Kroghs constant, K, and for this reason DL/VA is also known as KCO. <> Other institutions may use 10% helium as the tracer gas instead of methane. Routine reporting of Dlco corrected to normal with Va without fully understanding the implications is misleading and can cause clinicians to lose their clinical index of suspicion and underdiagnose diseases when in fact Dlco still is abnormal. You are currently on the Physiology, measurement and application in medicine. Importance of adjusting carbon monoxide diffusing capacity (DLCO) and carbon monoxide transfer coefficient (KCO) for alveolar volume. When factored in with a decrease in alveolar volume (which decreases the amount of CO available to be transferred), the rate at which CO decreases during breath-holding (for which KCO is an index) increases. Normal DLCO: >75% of predicted, up to 140% Mild: 60% to LLN (lower limit of normal) Moderate: 40% to 60% Severe: <40% What It is also often written as DLCO/VA (diffusing capacity per liter of lung volume) and is an index of the efficiency of alveolar transfer of carbon monoxide. These values may change depending on your age. Thank you so much again for letting me share my thoughts. A disruption of any of those factors reduces DLCO. extra-parenchymal restriction such as pleural, chest wall or neuromuscular disease), an increase in pulmonary blood flow from areas of diffuse (pneumonectomy) or localized (local destructive lesions/atelectasis) loss of gas exchange units to areas with preserved parenchyma; this frequently leads to more modest increases in KCO (although a high KCO can also be seen with normal VA when there is "increased pulmonary blood flow" or redistribution (e.g. Because it is not possible to determine the reason for either a low or a high KCO this places a significant limitation on its usefulness. %PDF-1.7 % A normal absolute eosinophil count ranges from 0 to 500 cells per microliter (<0.5 x 10 9 /L). The reason is that as the lung volume falls, Kco actually rises. Using helium as the inert gas, the concentration of the inhaled helium (Hei) would be known, and because the inhaled volume (Vi) is measured, measuring the concentration of exhaled helium (Hee) will give the volume of lungs exposed to helium, or Va, as follows: Vi is the volume of inhaled gas minus the estimated dead space (since dead space will not contain any helium). endobj A normal Dlco does not rule out oxygen desaturation with exercise. Because anemia can lower Dlco, all calculations of Dlco are adjusted for hemoglobin concentration to standardize measurements and interpretation.1 In the PFT laboratory, a very small amount of CO (0.3% of the total test and room air gases) is inhaled by the patient during the test, and the level is not dangerousCO poisoning with tissue hypoxemia does not occur with the Dlco measurement. 28 0 obj Since a low Q regardless of V can explain both hypoxia and a low DLCO Im not sure there needs to be a separate mechanism. 1 Introduction. Oxbridge Solutions Ltd receives funding from advertising but maintains editorial 0000006851 00000 n WebThe normal adult value is 10% of vital capacity (VC), approximately 300-500ml (68 ml/kg); but can increase up to 50% of VC on exercise Inspiratory Reserve Volume(IRV) It is the amount of air that can be forcibly inhaled after a normal tidal volume.IRV is usually kept in reserve, but is used during deep breathing. The key questions that should be asked include: Is the reduction in Dlco due to a reduction in Va, Kco, or both? 2006, Blackwell Publishing. Dlco can be normal or slightly decreased in extrinsic restrictive disorders (underlying lung physiology is normal except for atelectasis) such as Guillain-Barr syndrome, myasthenia gravis, amyotrophic lateral sclerosis, and corticosteroid-induced myopathy, given a decrease in Va but a normal to elevated Kco (Dlco/Va). endobj Hansen JE. Does that mean that the DLCO is underestimated when the VA/TLC ratio is low? endobj For the purpose of this study, a raised Kco was diagnosed only if it exceeded the predicted value for Kco (van How will I recover if Ive had coronavirus? endstream uuid:8e0822dc-1dd2-11b2-0a00-cb09275d6100 41 0 obj Simultaneously however, the pulmonary capillaries are also stretched and narrowed and the pulmonary capillary blood volume is at its lowest. Consultant. Dont worry if it takes several attempts to get a reliable reading. At end-exhalation (FRC), again the alveoli and pulmonary capillaries are at atmospheric pressure but the capillaries are mechanically relaxed and able to hold a greater amount of blood. Simply put, Dlco is the product of 2 primary measurements, the surface area of the lung available for gas exchange (Va) and the rate of alveolar capillary blood CO uptake (Kco).1,3 An understanding of how these 2 variables are determined provides important insight into the clinical implications of Dlco. The unfortunate adoption of certain nomenclature, primarily Dlco/Va (where Va is alveolar volume) can cause confusion on how Dlco assessment is best applied in clinical practice. 1. A decrease in Dlco in persons with HIV independently predicts the development of opportunistic pneumonia or pneumocystis pneumonia and is due to loss of capillary blood volume with regional air-trapping or early emphysema.7. The results can be affected by smoking, so if you are a smoker, dont smoke for 24 hours before your test. If your predicted KCO is derived from separate population studies I would wonder what effect re-calculating percent predicted DLCO and KCO using reference equations from a single study would have on your data and your expectations. At least one study has indicated that when the entire exhalation is used to calculate DLCO both healthy patients and those with COPD have a somewhat higher DLCO (although I have reservations about the studys methodology).
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